<?php
function total_number($f, $t, $str)
{
	$total = 0;
	$list = explode(",", $str);
	print_r($list);
	for($i = $f - 1; $i < $t - 1; $i ++)
	{
		if ($list[$i] == 1)
			$total ++;
	}
	return $total;
}
?>